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Some Investigations on the Phenomena of " Clot" Formations. 

 Part I. — On the Clotting of Milk. 

 By S. B. Schryvee. 



(Communicated by Prof. E. H. Starling, F.R.S. Received March 6, — Read 



April 10, 1913.) 



(From the Research Institute of the Cancer Hospital.) 

 Introduction. 



During the course of some researches on the bile acids, the observation 

 was made that sodium cholate in 1-per-cent. solution reacts with calcium 

 salts in a characteristic manner. On first addition of the salt solution, the 

 mixture remains clear ; on gentle warming, however, it solidifies to form an 

 irreversible gel, the rate of formation of which, other factors being the same, 

 is dependent on the temperature. A series of experiments was carried out 

 to ascertain what influence the concentrations of the various calcium salts 

 exerted on the time required for "clot" formation. These experiments were 

 carried out at a temperature of 50° C. It was found as a result, that the 

 calcium salts, as regards their behaviour to sodium cholate, could be divided 

 into two classes. In the first class are included those salts in the presence of 

 which the clotting time diminishes as the concentration of their solutions is 

 progressively increased. In the second class of salts, the clotting time also 

 diminishes as the concentration is increased, but only up to a certain optimal 

 point ; further concentration beyond this point increases the time of clot 

 formation, or even inhibits it entirely. The salts of the first class can be 

 distinguished from those of the second, in that the former increase the- 

 surface tension of water (measured against air), whereas the latter cause 

 a diminution of this constant. The greater the diminution of the surface 

 tension caused by salts of the second class, the smaller the range of con- 

 centration of the salt solution within which complete clot formation is 

 possible. The actual chemical nature of the clot has not yet been ascertained. 

 It is possibly either calcium cholate or the free acid (formed by hydrolysis of 

 the calcium salt) ; in either case it is obviously a heavily hydrated aggregate, 

 the formation of which is inhibited by the presence of readily adsorbed 

 substances ; the more easily such substances lower the surface tension of 

 water, the more readily are they adsorbed from aqueous solution, and the 



